Mike Schley is the illustrator of the map of Pyrrhia, although the original sketch was done by Tui T. Sutherland. His website is mikeschley.com.
Mike Schley also illustrated the updated map for books six through ten, the second arc of the Wings of Fire series; a different one for Darkstalker (Legends); and the map of Pantala.
Map for books 1-5, by Mike Schley
Map for books 6-10, by Mike Schley
Map for Darkstalker (Legends), by Mike Schley
Map of Pantala for books 11-15